Geological Atlas of the Western Canada Sedimentary Basin - Chapter 35

Chapter 35
Automated Data Processing for the Geological Atlas of the Western Canada Sedimentary Basin

Authors:
I. Shetsen - Agis Associates Ltd., Edmonton
G.D. Mossop - Geological Survey of Canada, Calgary

Introduction

Atlas computing and data processing embrace a multitude of operations on hundreds of data files and thousands of data elements, and involve scores of activities, ranging from the development of analytical techniques and associated software to painstaking construction of various map layers. This chapter provides a brief description of the essential elements of Atlas data processing and mapping; there is simply no space here to enumerate and describe all the methods, operations and steps involved in the production of Atlas maps. Procedures and techniques of general applicability are to be published separately, in the open literature. Details of the organization of the elements in the Atlas database are set out in the documentation that accompanies the digital release of Atlas data.

Much of what is presented here is intended for readers who are conversant with computer data processing and the mathematical and statistical methods employed in computer data analysis, including pattern recognition approaches.

Scope and Constraints

The Atlas mapping is based on voluminous digital subsurface data collected prior to 1987 and donated to the project by government agencies and private companies (Fig. 35.1). These databases contain comprehensive and systematic information on well stratigraphy and lithology, and provide exceptional to adequate control for virtually the entire Western Canada Sedimentary Basin. However, given the regional scale of Atlas mapping, utilization of the whole wealth of information poses several problems. The cost of converting vast volumes of records directly into map inputs and maps would be prohibitive. The density of drilling is uneven, and locally far exceeds the resolution of Atlas maps. The data contain a certain degree of redundancy and inconsistency, and require reassessment and culling prior to usage. To perform revisions on the scale of all of the original data would have been clearly beyond the available resources.

Consequently, the original data were evaluated, filtered and distilled into a manageable subset of approximately nine thousand Atlas control wells, selected on the basis of one representative well per township or equivalent area. To compensate for the inevitable loss of information induced by data reduction, the database was augmented by additional data sets, of both a generalized and a detailed nature, described below under Atlas Database.

The record of stratigraphic picks in Atlas control wells was substantially revised and refined by the chapter teams. The iterative process of database and map upgrading, outlined schematically in Figure 35.2, continued throughout the life of the project, using a combination of automated and manual data evaluation methods. The final Atlas maps, although compiled with considerable manual input, are an offspring of several generations of computer maps that were produced at project headquarters, and dispatched, together with accompanying computer-generated reports on data inadequacies, to chapter teams for review and correction. The revised/corrected data introduced into the database spurred the production of a new set of maps. Thus the procedure iterated until there was convergence on maps with which all parties were satisfied. Data processing and map compilation are discussed under Data Maintenance and Map Production, respectively.